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From:   Shakeel Butt <shakeelb@google.com>
Date:   Tue, 20 Aug 2019 09:48:40 -0700
Message-ID: <CALvZod7-dL90jwd2pywpaD8NfUByVU9Y809+RfvJABGdRASYUg@mail.gmail.com>
Subject: Re: [PATCH 00/14] per memcg lru_lock
To:     Michal Hocko <mhocko@kernel.org>
Cc:     Alex Shi <alex.shi@linux.alibaba.com>,
        Cgroups <cgroups@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Linux MM <linux-mm@kvack.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Mel Gorman <mgorman@techsingularity.net>,
        Tejun Heo <tj@kernel.org>, Hugh Dickins <hughd@google.com>
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On Tue, Aug 20, 2019 at 3:45 AM Michal Hocko <mhocko@kernel.org> wrote:
>
> On Tue 20-08-19 17:48:23, Alex Shi wrote:
> > This patchset move lru_lock into lruvec, give a lru_lock for each of
> > lruvec, thus bring a lru_lock for each of memcg.
> >
> > Per memcg lru_lock would ease the lru_lock contention a lot in
> > this patch series.
> >
> > In some data center, containers are used widely to deploy different kind
> > of services, then multiple memcgs share per node pgdat->lru_lock which
> > cause heavy lock contentions when doing lru operation.
>
> Having some real world workloads numbers would be more than useful
> for a non trivial change like this. I believe googlers have tried
> something like this in the past but then didn't have really a good
> example of workloads that benefit. I might misremember though. Cc Hugh.
>

We, at Google, have been using per-memcg lru locks for more than 7
years. Per-memcg lru locks are really beneficial for providing
performance isolation if there are multiple distinct jobs/memcgs
running on large machines. We are planning to upstream our internal
implementation. I will let Hugh comment on that.

thanks,
Shakeel